摘要:
A system for obtaining a propagation factor for determining the performance of a light beam (32) includes a light sensor (10), a lens element (30) operable to focus a beam from a light source to be tested towards the sensor element (10); wherein the lens element is a variable focus lens (30).
摘要:
A system for obtaining a propagation factor for determining the performance of a light beam (32) includes a light sensor (10), a lens element (30) operable to focus a beam from a light source to be tested towards the sensor element (10); wherein the lens element is a variable focus lens (30).
摘要:
A substrate includes a diffracting structure providing a hologram which encodes one or more holographic images. Every image of the one or more holographic images has a holographic location at either a finite or substantially infinite effective optical distance. The hologram is to be used as an ophthalmic eye chart or an eye exercise device or to provide a scale for measuring distances.